Unable to arm ESCs. Also unusual PWM.

I cannot arm ESCs in stabilize, acro and simple modes. Each turning on the green led stays off for about 5-10 secs, than green-red are blinking, and than green blinks (is this "one-time ESC test"?). Moving rudder left or right for 2-10 seconds does nothing, green still blinks.

I've downloaded the latest Mission Planner, burned APM with Arducopter 2.0.50 (quad X). There was no major issues in setup process. Except "Missing RC Rev param" alert, but the program correctly displayed the movement of Tx's sticks. Also, no reverse checkboxes saved. But I was able to adjust all necessary params in the transmitter. However, both modes selector and leveler were allright. Manual calibration passed as it was expected.

Automatic calibration: green led is not blinking, motors beep 123 instead of usual 123-1.-1..-1... and no calibration happen.

Connected to any of motor outputs with that abnormal PWM, it starts to slowly rotate motor, as at 1100-1200 CV. An analog servo, connected to the same output, have burned out in 5 minutes with very bad smell. And there's motor log:

not followed the links in your post above to see, but i have the same radio set-up and initially had a similar issue.
i fixed it by going into servo set-up on the DX8, select the throttle, and increase the travel param to 110% at each end of the range.
hope that helps

you will need to reset your esc's once you've done this - you probably know this - remove esc's from apm, and set up so you have esc connected top receiver and a motor, but no power to esc, switch radio on, full throttle, power to esc, hear beeps, throttle to min, hear beeps, done.